Those 'alternative methods of bleeding' I've posted here, come from here, and referenced a bmw TIS for an older car...I think E39.
I was surprised when I saw the label, I have to say, but it seems there's more than one way to skin a cat. Many old timers do bleed with car on...but they know what they're doing...and also, know to make sure the system is mostly full before starting!
Also, the bottle label says ET cap off...not bleeder screw open... My alt method, says cap and bleeder screw on...and you know with that, the engine isn't getting warm since it's only on for 20 secs.
I'll say this...I have a drain and wp install coming up...and I'm going to bleed the way in the TIS...the way Mango lists as from the TIS...the way that's in Bentley.
I've only recommended my alt method when someone has tried to rebleed after an initial fill...or just partial opening of the system. I've had a number here say it's worked for them, and I've done it successfully on other cars. It's a back stop method.